Prediction and Resolution of Vehicle In-Cab Noise due to Powertrain Induced Excitations

Vehicle NVH is one of the critical performance quality parameter and it consists of vibration levels at tactile points and noise levels at ear locations for different vehicle running conditions. There are many sources of noise and vibration in a vehicle, and powertrain is one of the main source. Therefore, it is important to understand and resolve powertrain induced noise and vibration issues at early design stage with efficient simulation techniques. The work presented here deals with the use of systematic CAE approach for prediction and resolution of structure borne in-cab noise due to powertrain excitations. During NVH testing of SUV vehicle, boom noise is observed at low frequency. Detailed full vehicle level simulation model consisting of vibro-acoustic trimmed BIW, front and rear suspension, and driveline with powertrain modal model is built. Powertrain dynamic loads due to inertia and combustion pressure are applied at powertrain C.G. and in-cab noise at driver ear location (DEL) is predicted. Predicted in-cab noise shows good correlation with measured 2EO noise. Root cause analysis shows that front sub-frame has vibration mode in the frequency range of issue. Based on simulation, conceptual modification of rigid plate between sub-frame and vehicle body is suggested and gives significant improvement in vehicle in-cab noise when tested. Using simulation approach, other feasible design solutions are worked out.